Rock drill lubricant containing a phos-



United States Patent ROCK DRILL LUBRICANT CONTAINING A PHOS- PHORUS ACE ESTER AND A SULFURIZED FATTY OIL Gordon S. Bright, Port Arthur, and Russell W. Hall, Houston, Tex., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application May 7, 1952, Serial No. 286,628

7 Claims. (Cl. 252-463) This invention relates to an improved lubricant for the lubrication of pneumatic tools, and more particu larly to a lubricating composition having superior lubricating properties which are obtained by means of an additive combination including a phosphorus acid ester and a sulfurized fatty oil.

Lubricants employed for the lubrication of pneumatic tools, such as rock drills, are required to have a special combination of properties including particularly both good extreme pressure properties in order to protect the tool parts from excessive wear due to high rotational loading, including shock loading, and very superior rust preventiveness to protect the tool parts from rusting under the conditions encountered in drilling operations. Since these lubricants often become contaminated with considerable quantities of water in service, particularly in wet drilling operations, they must have the property of emulsifying readily with water in order to resist being washed away from the lubricated parts.

The most generally satisfactory pneumatic tool lubricants employed up to the present time have been compounded oils comprising mineral oils containing about 10 per cent or more of blown rapeseed oil. Such compositions have the required lubricating characteristics for this type of service, including both good anti-wear properties and very superior emulsifiability. However, blown rapeseed oil is an expensive and increasingly scarce material, so that its use in high proportions in non-recirculated lubricating compositions of this type is undesirable from an economic standpoint, and in addition it has the further disadvantage of a pronounced odor, which is very objectionable when the lubricant is employed in a small enclosed place. It has therefore become commercially important to find a lubricant having .the desirable lubricating characteristics of the. blown rapeseed toil blends without these undesirable features. Attempts to obtain such a lubricant by employing other additives of various types have been heretofore generally unsuccessful, principally because of the mutually opposing effects of many extreme pressure agents and emulsifying agents. Thus, the phosphorus acid esters, which are commonly employed as anti-wear agents in other types of lubricating compositions, have a pronounced demulsifying effect, and severe rusting of the tool parts has been found when lubricants containing these compounds have been employed as pneumatic tool lubricants.

We have now found that a pneumatic tool lubricant which is fully equivalent in its lubricating properties to the blown rapeseed oil blends of the prior art, but without the objectionable features of the latter, may be obtained by the use in a suitable lubricating oil base of a special combination of additives comprising a phosphorus acid ester, a sulfurized fatty oil, a phosphatide emulsifying agent and a high molecular weight polymeric stringiness agent.

The mineral lubricating oil employed as the base oil in the above compositions is preferably a naphthenic or 2,734,868 Patented Feb. 14, 1956 mixed naphethenic and parafiinic refined oil having a viscosity in the range of from about 300 to about 700 seconds Saybolt Universal at F., although somewhat lower or higher viscosities may be employed to obtain lubricating compositions adapted for unusual operatingconditions. Ordinarily, an oil having a viscosity in the range of from about 400 to about 600 seconds Saybolt Universal at 100 F. is most suitably employed.

The phosphorus acidester is a compound chosenv from the Well-recognized class of extreme pressure compounds which comprises oil-soluble or oil-miscible esters of phosphoric and phosphorous acids, including alkyl, aryl and mixed: alkyl-aryl esters. The term phosphorus acid ester as employed herein will be. understood tomean a compound represented by the following formula:

wherein R is hydrogen or an aliphatic, aromatic or alicylic hydrocarbon group, with at least one R being hydrocarbon, and X is either an oxygen atomor is absent. Substituentgroups such as basic groups which have a deleterious eifect upon the extreme pressure properties of the compound should be absent. As examples of suitable compounds of thisclass may be mentioned dilauryl phosphate, tributyl phosphate, triamyl phosphite, tricresyl. phosphate, tricresyl phosphite, tricyclohexyl P1108. phate, trixylyl phosphate, trixylyI p'hosphite and dioctyl phosphate. Tricresyl phosphate is a particularly effective and readily available material of this character and may be regarded as the preferred compound for use in the lubricating compositions of the present invention. The phosphorus acid ester'may be employed in amounts ranging from about 0.2 to 3 per cent, and most suitably from about 0.5 to 2 per-cent by weight-of the lubricating composition.

The sulfurized fatty oil may be any sulfurized natural or synthetically obtained fatty material such as have been employed as lubricant additives of the non-corrosive sulfur type, such as for example as may be obtained by sulfurizing lard oil, castor oil, sperm oil, corn oil, fishv oil or the like. A particularly suitable material of this character is sulfurized lard oil containing from about 4 to 12 per cent of sulfur, obtained by heating No. 1 lard oil with about 10 to 15 per cent of sulfur at a temperature above 300 F., and preferably at about 350- 400 F., for a sufiicient time to obtain a homogeneous product. About 0.2 to 5 per cent, and preferably about 1 to 3 per cent of this sulfurized oil is employed in the lubricating composition of this invention.

The phosphatide employed as the emulsifying agent may be any phosphatide of vegetable or animal origin such as lecithin, cephalin or sphengomyelin, either in purified form or in the form of mixtures which are substantially free from impurities having emulsion-suppressing activity. A suitable and readily available material of this type is commercial soybean lecithin, such as the product known commercially as Lipoidol which consists essentially of about equal proportions of lecithin and cephalin with a smaller proportion of soybean oil. If desired, the commercial soybean lecithin can be purified, as by extracting the soybean oil with acetone to obtain a product consisting essentially of lecithin and cephalin. The lecithin and cephalin can also be separated by extracting the cephalin with alcohol, and either the purified lecithin' or the cephalin employed. The phosphatide may be employed in the lubricating compositions of the present invention in amounts of from about 0.1

to about 2 per cent, and most suitably in amounts of from about 0.2 to 1 per cent by weight of the composition.

The high molecular Weight polymeric stringiness agent may be a polymerized olefin or a polymerized oxygencontaining material such as polymers of vinyl ethers or polyesters of substituted fatty acids. isobutylene polymer having a Saybolt furol viscosity at 210 F. of about 1,000 to 2,000 seconds is particularly suitable for this purpose. Such polymeric material may be employed in amounts ranging from about 0.1 to about 3.0 per cent by weight of the composition.

We have found that lubricants of the above composition emulsify readily with water to form emulsions of good lubricating properties and in addition they are characterized by high load carrying and other properties, such as adhesiveness, oiliness, etc., necessary to maintain good lubrication under the severe conditions encountered in rock drilling, including high loads, rapid mechanical jarring, impingement of high velocity gases and large temperature variations. They have the further advantage of being obtained from relatively inexpensive and readily available materials and are substantially free from objectionable odor.

As an example of a lubricating composition of this invention, a lubricant was prepared having the following composition in per cent by weight:

Sulfurized lard oil 2.0 Tricresyl phosphate 1.0 Lecithin 0.25 Isobutylene polymer 1.0 Lubricating oil Remainder The lubricating oil base was a blend in a 43 :57 volume ratio respectively of a light lubricating oil and a heavy Both oils were lightly refined distillate fractions from a predominantly naphthenic base crude.

The sulfurized lard oil contained 7.29 per cent of sulfur, and was obtained by heating No. 1 lard oil with powdered sulfur at about 300 F. for 4 hours.

The tricresyl phosphate was a commercial mixture of para, meta and ortho derivatives, obtained from coal tar acids.

The isobutylene polymer, which was employed as a stringiness agent, was a semi-plastic material having a Saybolt Furol viscosity at 210 F. of 1400 seconds.

The lubricant was prepared by mechanically mixing the additives into the lubricating oil base at a temperature of 130-180 F.

The above lubricant has been field tested extensively in various types of rock drilling operations, including such operations carried out under very severe conditions, and in all cases it has proved to be an outstandingly superior lubricant for this type of service. In an initial test, it was employed to lubricate four Gardner Denver S45 jack hammers for 60 days in a wet drilling operation. A total distance of 3,624 feet was drilled during this test, through rock structure varying from medium hard to very hard. At the end of the test, all internal parts of the drills were found to be well coated with oil, which was partly in the form of a milky emulsion with water. No rusting or corrosion of the metal parts had occurred, and only a very slight amount of Wear (about 0.003 inch) was found on the rifle nuts on the loaded side of the teeth, this amount of wear corresponding to a calculated rifle nut life of over months. These results were fully equivalent to those obtained in the same test employing one of the best commercial lubricants of the blown rapeseed oil type. With good grade commercial lubricants of other types, containing other additives of various types in place of the blown rapeseed oil, a rifle nut life of only slightly better than one month is ordinarily obtained in this drilling operation. With a commercial lubricant containing a phosphate ester as an anti-wear agent but without any sulfurized fatty oil, severe rusting of the rifle bars, nuts and other parts occurred, and replacing of the rifle nuts in as little as ten days was sometimes necessary. 0

Obviously, many modifications and variations of the invention, as heerinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A pneumatic tool lubricant consisting essentially of a mineral lubricating oil having a viscosity in the range of from about 300 to 700 seconds Saybolt Universal at F., containing about 0.2 to 3.0 per cent by weight of a phosphorus acid ester selected from the class of oil-soluble and oil-miscible diand trialkyl, aryl and mixed alkyl-aryl phosphates and phosphites, about 0.2 to

5.0 per cent by weight of a non-corrosive sulfurized fatty oil containing at least about 4 per cent by weight of combined sulfur, about 0.1 to 1.0 per cent by weight of a phosphatide emulsifying agent selected from the class consisting of lecithin, cephalin and sphengomyelin, and about 0.1 to 3.0 per cent by weight of a high molecular weight polymeric stringiness agent selected from the class consisting of olefin polymers vinyl ether polymers and polyesters of substituted fatty acids, said stringiness agent having a Saybolt furol viscosity at 210 F. of about 1,000 to 2,000 seconds. 7

2. Claim 1 wherein the phosphorus acid ester is tricresyl phosphate.

3. Claim 1 wherein the sulfurized fatty oil is sulfurized lard oil containing about 4-12 per cent of combined sulfur.

4. Claim 1 wherein the emulsifying agent is lecithin.

5. Claim 1 wherein the polymeric stringiness agent is an isobutylene polymer.

6. A pneumatic tool lubricant consisting essentially of a refined mineral lubricating oil having a viscosity in the range of from about 400 to 600 seconds Saybolt Universal at 100 F., about 0.5 to 2.0 per cent by weight of tricresyl phosphate, about 0.5 to 3.0 per cent by weight of sulfurized lard oil containing about 4 to 12 per cent by weight of sulfur, about 0.1 to 0.5 per cent by weight of lecithin, and about 0.5 to 2.0 per cent by weight of isobutylene polymer having a Saybolt furol viscosity at 210 F. of about 1,200 to 1,600 seconds.

7. A pneumatic tool lubricant consisting essentially of a refined mineral lubricating oil having a viscosity in the range of from about 300 to 700 seconds Saybolt Universal at 100 EX, about 0.2 to 3.0 per cent by weight of tricresyl phosphate, about 0.2 to 510 per cent by weight of a sulfurized fatty oil containing about 4 to 12 per cent by weight of sulfur, about 0.1 to 1.0 per cent by weight of a phosphatide emulsifying agent selected from the class consisting of lecithin, cephalin and sphengomyelin, and about 0.1 to 3.0 per cent by weight of an olefin polymer having a Saybolt furol viscosity at 210 F. ofabout 1,000 to 2,000 seconds.

References Cited in the file of this patent UNITED STATES PATENTS 2,179,067 Smith Nov. 7, 1939 2,228,429 Wright Jan. 14, 1941 2,322,859 Loane et a1 June 29, 1943 

1. A PNEUMATIC TOOL LUBRICANT CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL HAVING A VISCOSITY IN THE RANGE OF FROM ABOUT 300 TO 700 SECONDS SAYBOLT UNIVERSAL AT 100* F., CONTAINING ABOUT 0.2 TO 3.0 PER CENT BY WEIGHT OF A PHOSPHORUS ACID ESTER SELECTED FROM THE CLASS OF OIL-SOLUBLE AND OIL-MISCIBLE DI- AND TRI- ALKYL, ARYL AND MIXED ALKYL-ARYL PHOSPHATES AND PHOSPHITES, ABOUT 0.2 TO 5.0 PERCENT BY WEIGHT OF A NON-CORROSIVE SULFURIZED FATTY OIL CONTAINING AT LEAST ABOUT 4 PER CENT BY WEIGHT OF COMBINED SULFUR, ABOUT 0.1 TO 1.0 PER CENT BY WEIGHT OF A PHOSPHATIDE EMULSIFYING AGENT SELECTED FROM THE CLASS CONSISTING OF LECITHIN, CEPHALIN AND SPHENGOMYELIN, AND ABOUT 0.1 TO 3.0 PER CENT BY WEIGHT OF A HIGH MOLECULAR WEIGHT POLYMERIC STRINGINESS AGENT SELECTED FROM THE CLASS CONSISTING OF OLEFIN POLYMERS VINYL ETHER POLYMERS AND POLYESTERS OF SUBSTITUTED FATTY ACIDS, SAID STRINGINESS AGENT HAVING A SAYBOLT FUROL VISCOSITY AT 210* C. OF ABOUT 1,000 TO 2,000 SECONDS. 